Method and apparatus for providing position-related information to mobile recipients

ABSTRACT

A system for providing position-related information to a mobile user includes a mobile unit and a central site server. The mobile unit includes circuitry for determining present position information from position signals which may emanate from, for example, GPS satellites. The mobile unit further includes circuitry for establishing a wireless bidirectional communications link with the central site server via a terrestrial network, which may be accessed via a cellular telephone network. The central site server includes circuitry for receiving the present position information from the mobile unit. A table stored at the central site server includes different response information in correspondence with possible positions of the mobile unit. The response information may further be in correspondence with user preferences. The central site server uses the received present position information to retrieve corresponding response information from the table, and sends the retrieved response information to the mobile unit via the bidirectional communications link. The mobile unit further includes circuitry, such as a loudspeaker, for supplying the response information to the mobile user. In another aspect of the invention, communications between the mobile unit and the central site server are encrypted. Furthermore, the mobile unit may include components for preventing position information from being supplied to the loudspeaker, thereby eliminating distracting noise from being presented to the user.

This application is a continuation of U.S. application Ser. No.08/698,148, filed Aug. 15, 1996, now U.S. Pat. No. 6,199,045.

BACKGROUND

The invention relates to mobile information systems, and moreparticularly to systems and methods for providing information to mobileusers, which information is based upon the user's position and tailoredto the user's interests.

For a number of reasons, it may be desirable to dynamically provide amobile user with information that is particularly related to the user'spresent location. Such reasons may include, but are not limited to, thedesire to assist and/or inform the user as he or she tours a particularlocale or exhibit, and the desire to assist the user as he or sheattempts to navigate from one location to another. A number oftechniques for providing such position-related information are known,and will now be described.

To begin with, a variety of methods have been employed for the purposeof presenting observers with information that is related to exhibits(e.g., art displays, zoological displays, and the like) or sights (e.g.,tours of historic sights, natural wonders, urban settings, theme parks,and the like) which are in the proximate vicinity of the observer andfor guiding or controlling the observer's physical movements through anexhibit, display, or geographic locale. The most common and most widelyused of these presentation and touring methods include:

-   -   Guided tours in which the customer accompanies a tour guide on a        walking tour or in a vehicle (e.g., bus, boat, helicopter);    -   Personal tours in which the sightseer reads a brochure and        follows a map or floor plan;    -   Personal tours in which the sightseer reads informative sign        boards, or obtains information from a kiosk or diorama;    -   Loudspeaker broadcasts of information at preselected (i.e.,        fixed) locations;    -   Portable playback devices rented by the sightseer which play an        audio tape, compact disk, or video tape; and    -   Portable receivers rented by the sightseer which trigger short        range infrared (or similar technology) transmitters located at        various points of the exhibit, and which play back a description        keyed to the location of the transmitter.

The above-mentioned techniques variously suffer from one or more of thefollowing drawbacks: 1) a lack of automation, such as in the case ofhuman tour guides; 2) a failure to detect the user's location, therebyrequiring the user to expend some effort to ensure receipt of theappropriate information at the right time; 3) an inability to provideinformation at more than a few fixed locations; and an inability of theuser to select the type of information that will be received at anygiven location.

Recognizing the increasing mobility of society and the growing need andquest for concise, rapid, accurate and readily available information,the proprietors of information and entertainment venues, aircraft andautomobile manufacturers, electronic equipment providers, andrecreational equipment providers have attempted to install or provideaccess to on-demand information. These providers have come to realizethat people prefer on-the-spot information at a time and place of theirown choosing that is relevant to their current location and tailored totheir particular interests.

Several types of devices and equipment have been created which haveattempted to afford the user freedom from interpreting written material.Guided and unguided tours, for example, employ pre-positioned audio andvideo information which is delivered when the user either pushes abutton to announce his presence or when his approach is detected by thetriggering of a sensor. Such a system readily determines that a vieweris at a particular predefined location. However, the system is limitedin that position-based information is restricted to those locations atwhich the provider can economically and practically position the sensorstations. Users who are proceeding in a vehicle or are, of necessity,continually on the move either cannot maintain contact with the fixedinformation source or will quickly find themselves located at a pointwhere the provided information is no longer relevant. Another drawbacksterns from the fact that the quality of the audio or video at fixedstations is dependent on close proximity to the location, and tends todeteriorate with continuous usage.

Tour bus and van manufacturers have installed audio and visual deviceswhich can provide position related tour and scenic information keyed tothe vehicle's location as determined by the driver or tour guide.Listeners use channel selectors mounted to their seats to select whatprerecorded information they will receive in their headsets or monitors.This system provides whatever information the tour company haspreselected and the staff must either continually correlate the contentwith the position of the vehicle or prepare a sequential presentation ofcontent that will hopefully match the predicted position of the vehicle.

A class of individual and personal mobile information systems have alsobeen created based on “on-board” storage technologies and the use ofsigns, sensors, and user inputs to establish the current position of thevehicle or individual. The position information, which may beautomatically obtained via the fixed sensor or else manually determinedby the individual from external signs, maps, and the like, and thenentered by means of a keyboard or selection switch, triggers theplayback device to output the corresponding audio or visual informationstored locally (on-board or on the individual) on an audio cassette,compact disk (CD) read only memory (ROM), compact disc, or similarstorage system.

The drawback with systems whose position information is derived fromfixed sensors and signs is that they tend to be obtrusive and, as apractical matter, the scope of their coverage is limited to thoselocations where they may be feasibly and legally placed.

The drawback with on-board systems requiring user involvement in thedetermination and inputting of current location is that the conduct ofthese activities may be distracting and even dangerous, particularly ifthe user is mobile and responsible for the safe control of a vehicle.

The advent of universal and accurate navigation systems, such as theglobal positioning system (GPS), has made it possible to rapidlydetermine the position of a mobile object or individual with highprecision. For background information on these techniques, reference maybe made to U.S. Pat. No. 4,114,115 and its included references. Briefly,a plurality of artificial satellites are utilized so that at least fourobserved satellites are always capable of providing a mobile receiverwith a meaningful signal with which to determine orbiting data of eachsatellite. The present position of each satellite is obtained byapplying detected orbit data to solve Kepler's equation. A distance fromthe ground-based mobile object to each satellite can be obtained bymeasuring the propagation time of the signal transmitted from thesatellite. The mobile receiver's present position is determined by thesolution of simultaneous equations relating the position of each of themultiple satellites with the distance between the mobile receiver andeach respective observed satellite. The resulting position informationis displayed to the user as his location at the time of observation.

Such capabilities enable accurate and rapid determination of currentposition by people at fixed positions or on the move. The advent of thistechnology means that the traveler need no longer be dependent uponpre-positioned sensors or upon the manual determination and inputting ofcurrent location to provide the position trigger for information sourcessuch as those described above. As a result, a number of systems havebeen devised which allow the occupant of a mobile vehicle to retrieveinformation contained on an installed cassette tape, compact disk orsimilar storage device, which information is based on the accurate GPSposition data entered into an onboard computer. Such systems areparticularly suited for mobile navigation as employed, for example, inthe system described in U.S. Pat. No. 5,396,254. This systemincorporates a position recognition system and an onboard map orlocation database. While this system provides map information generatedfrom an onboard database including the display of the mobile unit'scurrent position and surrounding geographic features, another systemdescribed in U.S. Pat. No. 5,410,486 goes further to display onboardgenerated routing information for locations specified by the operator.Yet another system is described in U.S. Pat. No. 5,406,492, whereinaudio instructions derived from an onboard computer processing unit(CPU) are provided to the traveler to effect preselected routing,thereby freeing the operator from interpreting visual instructions andpictorial information as required in the system described in U.S. Pat.No. 5,410,486.

Also known in the art is a personal guidance system for blindpedestrians developed by Jack Loomis, Reginald Golledge, and RobertaKlatzky, as described in P. Tyson, “High-Tech Help for the Blind”,Technology Review pp. 19-21, April 1995. As described in this article,the system incorporates a GPS monitor, laptop computer, headphones, andassociated equipment into a twenty-eight pound backpack unit which isintended to be worn by a blind pedestrian. As the pedestrian walksthrough an area, the GPS information is used by the computer toretrieve, and deliver to the user, audio information indicating thestructures and landmarks in current proximity to the pedestrian.

The disadvantage in each of these systems is that the derivation ofinformation from an on-board storage device necessitates the collectionand entry of that information into the computer's mass storage devicelong before the journey is commenced. Consequently, the routing guidanceand other information is based on static information from the moment itis entered into the database of the onboard system. If the informationis of a perishable nature, such as in the nature of highway trafficconditions, construction and repair progress, seasonal availability orcost information, the on-board database is only as good as the mostrecent edition received and loaded by the user.

Equally limiting is the scope and breadth of the onboard database.Normally entered into a finite space and capacity, any travel beyond thedimensions of the loaded data is of necessity unsupported by theinstalled information system.

Furthermore, in the case of the personal guidance system for blindpedestrians, the employment of “on-board” processing and storage of theinformation database necessitates that the pedestrian constantly carrythe “on-board” equipment from location to location.

The limitations suffered by solutions relying on on-board informationstorage systems are partially addressed in U.S. Pat. No. 4,812,843 toChampion et al. In a described embodiment, this traffic informationsystem permits direct access to information maintained and kept currentby a service provider. Information concerning the current status oftraffic conditions along a specific metropolitan commuter route ismaintained in a high capacity dynamic data base and is available tocustomers on demand. Additional information reports which may be ofinterest to a subscriber, including airline flight and surface travelinformation as well as stock information, may be queried. Subscribersare provided such information by wireline telephone, mobile telephone,or computer.

The employment of a centralized information system which is remotelylocated from the mobile vehicle solves the problem of local storagelimitations and additionally permits the provider to rapidly update theinformation disseminated to customers. However, the system described inU.S. Pat. No. 4,812,843 requires that subscribers personally determinetheir current position and provide that position information via theinput device, whether that be digitally via modem or via a dual tonemultiple frequency (DTMF) capable telephone. In addition, the travelinformation system is geared specifically toward urban vehicularcommuters by providing information on traffic conditions and optimumrouting given those conditions. The system does not address the needs ofpedestrians including tourists, travelers, students, and the localpopulace in general for a broad range of position-dependent informationin urban, rural or remote locations.

As described in Better Homes and Gardens p. 214, July 1995, anotherknown system utilizes GPS technology to locate the current position of avehicle and to use this information provide an emergency service. At thetouch of a button, buyers of the 1996 Lincoln Continental automobile(manufactured by the Ford Motor Company) will be able to access aworldwide emergency tracking system. This system, which is known as theRemote Emergency Satellite Cellular Unit (RESCU), uses globalpositioning satellite technology and the cellular phone network to put adriver in voice contact with an operator at a special response center.The operator at the response center pinpoints the vehicle's location,guides the appropriate emergency service to the vehicle, and stays invoice communication with the customer until help arrives. A specialpassword setup protects against false alarms or unauthorized attempts toturn the system off.

In essence, the RESCU system provides an enhanced version of thestandard 911 emergency call in which the location of the customer isautomatically relayed to the emergency center instead of being verballycommunicated by the customer over the voice circuit. As such, the RESCUsystem is an emergency service for vehicular customers that utilizes GPSpositioning technology. It should be noted, however, that theinformation content received by the customer is in all relevant aspectsidentical to that which would be received by a customer using a wirelineor cellular phone to make a standard 911 call. That is, the informationis not automatically retrieved from a data base as a function of thecaller's position, but rather is whatever the operator at the responsecenter happens to say to the caller. Thus, the position information isonly relevant with respect to the dispatch of emergency personnel and islargely unrelated to the information content received by the vehicularcustomer. Additionally, the RESCU system is designed specifically toserve customers riding in properly equipped automobiles and is notapplicable to pedestrians in-distress.

SUMMARY

It is therefore an object of the present invention to provide a systemthat delivers information which is related to the accurate position ofthe information seeker.

It is another object of the invention to provide the position-relatedinformation with minimal effort expended by the user in determining hisaccurate position.

It is yet another object of the invention to provide user-selectableposition-related information on a broad range of topics or interests.

It is still another object of the invention to provide position-relatedinformation to users who may be anywhere in a broad geographic areaserved by mobile communications providers.

It is yet another object of the invention to provide position-relatedinformation on a continuous basis at any hour or in any climaticcondition.

It is still another object of the invention to provide dynamicallychangeable position-related information by means of a fully automated,centrally maintained facility to ensure accuracy, completeness andtimeliness.

It is yet another object of the invention to provide a position-relatedinformation delivery service to users (vehicle occupants or pedestrians)by means of lightweight, highly portable and easily employed equipment.

It is still another object of the invention to extend theposition-related information delivery service to third parties insupport of emergency and life support actions on behalf of thesubscriber.

It is yet another object of the invention to provide a position-relatedinformation delivery service to subscribers in a mode requiring minimalvisual observation and interpretation on the part of the subscribers.

It is another object of the invention to provide a position-relatedinformation delivery service that supports the presentation of text,graphics, and images to subscribers.

Further objects and advantages of the invention are to provide aposition-related information delivery service which is unobtrusive tothe environment surrounding the user, safely employable, expandable toall areas where wireless communications capability may extend, availableto collocated and interested travelers, and which is responsive toemergency conditions and supportive of regional or national emergencyplanning.

In accordance with one aspect of the present invention, the foregoingand other objects are achieved in an apparatus for providingposition-related information to a mobile user. The apparatus comprises amobile unit and a central site server. The mobile unit includes meansfor receiving position signals; means for determining present positioninformation from the position signals; and wireless means forestablishing a bidirectional communications link with a central siteserver via a terrestrial network. In a preferred embodiment, thebidirectional communications link is established through a cellulartelephone network coupled to a public switched telephone network orpublic data network. The mobile unit further includes means for sendingthe present position information to the central site server via thebidirectional communications link; means for receiving responseinformation from the central site server via the bidirectionalcommunications link; and means for supplying the response information tothe mobile user. The central site server comprises means for coupling tothe terrestrial network; means for receiving the present positioninformation from the mobile unit via the bidirectional communicationslink; means for storing a plurality of response information, eachresponse information corresponding to a particular position; means forusing the received present position information to retrievecorresponding response information from the storing means; and means forsending the retrieved response information to the mobile unit via thebidirectional communications link.

In another aspect of the invention, the central site server supplies themobile unit with a menu of user information-type possibilities. The usermakes a selection by, for example, pressing a key on the mobile unit'skeypad, and thereby generates a menu selection signal. The menuselection signal is then sent to the central site server via thebidirectional communications link. The central site server receives themenu selection signal from the mobile unit via the bidirectionalcommunications link, and uses this in conjunction with the positioninformation to retrieve corresponding response information from thestoring means.

In another aspect of the invention, communications between the mobileunit and the central site server are encrypted. Accordingly, the mobileunit's means for sending the present position information to the centralsite server comprises means for encrypting the present positioninformation; and means, coupled to the encrypting means, for sending theencrypted present position information to the central site server.Furthermore, the mobile unit's means for receiving response informationfrom the central site server comprises means for receiving encryptedresponse information from the central site server; and means, coupled tothe encrypted response information receiving means, for decrypting theencrypted response information. The central site server's means forreceiving the present position information from the mobile unitcomprises means for receiving the encrypted present position informationvia the bidirectional communications link; and means, coupled to theencrypted present position information receiving means, for decryptingthe encrypted present position information. The central site server'smeans for sending the retrieved response information to the mobile unitcomprises means for encrypting the retrieved response information; andmeans, coupled to the retrieved response information encrypting means,for sending the encrypted retrieved response information to the mobileunit via the bidirectional communications link.

In accordance with another aspect of the invention, the mobile unitfurther comprises means for receiving a request position command fromthe central site server via the bidirectional communications link; andmeans, coupled to the present position determining means and to therequest position command receiving means, for causing the presentposition determining means to initiate operation in response to receiptof the request position command. Furthermore, the central site serverfurther comprises means for sending the request position command to themobile unit via the bidirectional communications link.

In yet another aspect of the invention, the mobile unit furthercomprises a timer; and means, coupled to the timer, for periodicallysending updated position information to the central site server via thebidirectional communications link. The mobile unit may also includemeans for receiving a position refresh interval value from the centralsite server via the bidirectional communications link; and means forloading the position refresh interval value into the timer. In thisembodiment, the central site server further comprises means for sendingthe position refresh interval value to the mobile unit via thebidirectional communications link. In this way, the position refreshrate of the mobile unit can be set by the central site server.

In an alternative embodiment, the mobile unit further comprises meansfor receiving a position refresh interval value from the mobile user;and means for loading the position refresh interval value into thetimer. Thus, in this embodiment, the user has control of the positionrefresh rate.

In other aspects of the invention, the mobile unit may process theposition information to generate position coordinates, which are sent tothe central site server. Alternatively, the position signals themselvesmay be transmitted from the mobile unit to the central site server. Inthis case, the central site server has the ability to generate positioncoordinates from the position signals.

In still another aspect of the invention, the position-relatedinformation distribution system may be used for providing assistance inemergency situations. That is, the central site server may furtherinclude means for establishing a second communications link with anoperator via the terrestrial network. The operator may be, for example,an emergency service provider. The central site server may furtherinclude means for sending the present position information to theoperator via the second communications link; and means for transferringthe bidirectional communications link to enable communication directlybetween the mobile unit and the operator. With this arrangement, theuser may be in direct contact with an emergency service provider, andthe emergency service provider may receive up-to-the-minute informationabout where the user is.

In other aspects of the invention, the mobile unit may alternatively beconfigured to send/receive analog data and voice over either an analogor digital wireless infrastructure or to send/receive digital data andvoice packets over a digital wireless communications infrastructure.Also, the mobile unit may include isolation means for preventing thepresent position information from being supplied to a loudspeaker in themobile unit, thereby eliminating distracting noise from being presentedto the user.

Furthermore, the mobile unit may periodically send updated positioninformation to the central site server. The rate at which information isrefreshed may be set by the user, or alternatively set by the centralsite server. In the latter case, the central site server sends therefresh rate to the mobile unit via the bidirectional communicationslink.

In another aspect of the invention, the mobile unit may be provided witha switch to allow the user to alternatively enable or disable operationof the present position information sending means.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will be understood byreading the following detailed description in conjunction with thedrawings in which:

FIG. 1 is a block diagram of a system for delivering position-relatedinformation to a mobile user in accordance with one embodiment of theinvention;

FIG. 2 is a diagram of a selection/position table in accordance with oneaspect of the invention;

FIGS. 3A and 3B depict a flowchart of the operation of an exemplaryembodiment of the inventive position-related information delivery systemin accordance with an analog embodiment of the invention;

FIG. 4 is a block diagram of an exemplary mobile unit for use in ananalog position-related information delivery system;

FIG. 5 is a block diagram of an exemplary embodiment of a central siteserver for use with an analog embodiment of the invention;

FIGS. 6A and 6B depict a flowchart of the operation of a mobile unit anda central site server in accordance with a digital embodiment of theinvention;

FIG. 7 is a block diagram of an exemplary mobile unit for use in adigital position-related information delivery system; and

FIG. 8 is a block diagram of an exemplary embodiment of a central siteserver for use with a digital embodiment of the invention.

DETAILED DESCRIPTION

The various features of the invention will now be described with respectto the figures, in which like parts are identified with the samereference characters.

An exemplary embodiment of a system for delivering position-relatedinformation to a mobile user will now be described with respect to FIG.1. The exemplary system includes a cellular telephone network 101 forproviding mobile communications service to a mobile unit 103 locatedanywhere within a predefined geographical cellular service area. Inalternative embodiments, other types of mobile communications systemsmay be substituted for the cellular telephone network 101, such as lowearth orbit satellite communications systems in which a satellite may bein direct communication with the mobile unit 103. A more detaileddescription of the various mobile communications systems mentionedabove, which are well-known, is beyond the scope of this discussion.

The cellular telephone network 101 is coupled to a terrestrial network105, and is capable of initiating and receiving calls to and from theterrestrial network 105 in accordance with known techniques. Theterrestrial network may be, for example, a public switched telephonenetwork (PSTN).

In accordance with one aspect of the invention, a central site server107 is provided which has a private branch exchange (PBX) that isaccessible by way of the terrestrial network 105. The central siteserver 107 is also supplied with a voice response unit (VRU) forproviding voice oriented service. If data oriented service is to beprovided, the central site server 107 may alternatively have a remoteaccess server that is accessible by way of the terrestrial network. Theprimary purpose of the central site server 107 is to determine thenature of the information being requested by the mobile unit 103, and toselect, from the type of information requested, that subset ofinformation which is related to the mobile unit's present geographicallocation. Information about the mobile unit's present geographicallocation may be derived by means of known equipment, located within themobile unit 103, for processing GPS signals received from GPS satellites109. A detailed description of this well-known position-determiningprocessing is beyond the scope of this description.

In the illustrative embodiment, the position information identifies themobile unit 103 as being located within any one of the geographicalareas identified as A1, A2, A3, B1, B2, B3, C1, C2 and C3. In theexample, the mobile unit 103 is located in geographical area A2. Ofcourse, in practice the number of geographical areas may be fewer ormany more than the nine illustrated. After obtaining the informationtype and position information, the central site server 107 selects theappropriate subset of information 203 from a selection/position table201, as illustrated in FIG. 2. The selected subset of information 203 isthen transmitted to the mobile unit 103, as described in greater detailbelow.

A more detailed description of the operation of the exemplary systemwill now be described with respect to the flowchart depicted in FIGS. 3Aand 3B, and an exemplary embodiment of a mobile unit 103, which isdepicted in FIG. 4. In this first-described embodiment, the cellulartelephone network 101, as well as the circuitry within mobile unit 103which communicates with the cellular telephone network 101, utilize ananalog protocol, such as the Advanced Mobile Phone Service (AMPS) whichis utilized in the United States. The description herein refers only toselect components of the mobile unit 103. However, it should beunderstood that the mobile unit 103 also includes all of the customarycomponents of a standard analog cellular phone. Because such componentsare well known, they are not described here in detail.

This discussion will first focus on an exemplary embodiment of a mobileunit 103 for use in the analog system described above. Referring to FIG.4, the mobile unit 103 includes circuitry for combining cellulartelephone components with components necessary for interacting with thecentral site server 107. In connection with the cellular telephonecomponents, the mobile unit 103 includes a cellular antenna 405, whichacts as a wave guide for transmission and receipt of analog cellularradio frequency (RF) signals. The cellular antenna 405 is coupled toexchange the analog cellular RF signals with an RF modulator/demodulator407. The RF modulator/demodulator 407 modulates outgoing analog signalsonto cellular carrier radio frequencies in accordance with knowntechniques. One source of those outgoing signals is a microphone 409,which senses audio signals in the vicinity of the mobile unit 103.Another source of outgoing signals is a dual-tone multifrequency (DTMF)generator 411. One input of the DTMF generator 411 is coupled to receivesignals from a keypad 413. The DTMF generator 411 converts the keypadsignals into analog tones in accordance with known techniques.

Another function of the RF modulator/demodulator 407 is to demodulateincoming analog signals from cellular carrier radio frequencies tobaseband frequencies that are used by the mobile unit 103. Thedemodulated signals are supplied to a loudspeaker 415, which generatesaudible soundwaves that the user can hear. The mobile unit 103 may alsobe supplied with a headset 417 which allows the user to listen to theaudio information without disturbing others and without having to holdthe mobile unit 103 up to his ear for prolonged periods of time. Thoseskilled in the art will recognize that the loudspeaker 415 and theheadset 417 are each means for supplying information to the mobile user,and that alternative embodiments may include other well-known means forperforming this function.

Turning now to the components that provide the capability of interactingwith the central site server 107, the mobile unit 103 further includes aGPS antenna 401 which acts as a wave guide for receipt of wireless GPSposition signals. The GPS antenna 401 is coupled to supply these signalsto a GPS receiver 403. It will be recognized that the GPS signalsemanate from a plurality of GPS satellites 109 in accordance with knowntechniques.

The GPS receiver 403 converts the GPS signals into signals whichrepresent the geographic position of the mobile unit 103. If enhancedresolution of the mobile unit's position is required, differential GPStechniques may be employed. The output of the GPS receiver 403 issupplied to an input of the DTMF generator 411, so that the positioninformation can be transmitted, through the RF modulator/demodulator407, cellular network 101 and terrestrial network 105 to the centralsite server 107.

The GPS receiver 403 is controlled by a control unit 431 and by positionrefresh circuitry 419. The control unit 431 is responsible for enablingand disabling overall operation of the GPS receiver 403. The positionrefresh circuitry 419 causes the GPS receiver 403 to receive and processposition information at periodic time intervals which may be predefined,or which may alternatively be dynamically set.

To coordinate the actions of the mobile unit's cellular telephonecomponents with those of the central site server-related components, themobile unit 103 is further equipped with a remote DTMF isolation switch433, a DTMF receiver 435, and a position subsystem interface (I/F)module 421. The RF modulator/demodulator 407 supplies an audio inputsignal to the remote DTMF isolation switch 433, which in turn suppliesthis signal to the DTMF receiver 435 and to the loudspeaker 415. TheDTMF receiver 435 supplies this signal to the control unit 431 and tothe position subsystem I/F module 421. An output of the control unit 431is supplied to the remote DTMF isolation switch 433 to permit disablingof the remote DTMF isolation switch's output to the loudspeaker 415 orto the DTMF receiver 435. The position subsystem I/F module 421 iscoupled to receive signals that are derived from the RFmodulator/demodulator 407. In particular, the signals that the positionsubsystem I/F module 421 receives from the DTMF receiver 435 include theposition request command and refresh interval transmitted by the centralsite server 107 (see description of FIGS. 3A and 3B, below). Each ofthese signals is transmitted by the central site server 107 in the formof DTMF tones.

The position subsystem I/F module 421, then, includes circuitry toenable it, during operation, to receive an initial position requestcommand and a position refresh time interval value transmitted by thecentral site server 107, and, in response, to cause the position refreshcircuitry 419 to initiate a position report. The position subsystem I/Fmodule 421 also provides the position refresh circuitry 419 with thevalue of the received refresh interval, so that the position refreshcircuitry 419 will repeat the position reporting function once everyrequested time interval.

The coupling between the position refresh circuitry 419 and the positionsubsystem I/F module 421 is bidirectional, so that the positionsubsystem IF module 421 may receive notification of a pending positionrefresh from the position refresh circuitry 419. In another aspect ofthe invention, the mobile unit 103 is further equipped with aloudspeaker/headset isolation circuit 423 which controls a switch 425that is interposed between the output of the DTMF generator 411 and aninput of the loudspeaker 415. This configuration allows the control unit431 to cause the loudspeaker/headset isolation circuit 423 to preventthe sound of the internally-generated DTMF tones from emanating from theloudspeaker 415 (and/or the headset 417). It will be recognized thatthese DTMF tones represent the GPS position data that is beingtransmitted to the central site server 107. Were the loudspeaker/headsetisolation circuit 423 not provided, then the GPS position data wouldperiodically intrude upon the desired information being supplied to theuser whenever a position refresh operation were performed.

Similarly, a microphone isolation circuit 437 and microphone switch 439are provided to allow the output of the microphone 409 to bedisconnected from the input of the RF modulator/demodulator 407. Themicrophone isolation circuit is controlled by a signal supplied by thecontrol unit 431.

In accordance with another aspect of the invention, the control unit 431is also coupled to receive a signal from a position reportingenable/disable switch 427. The signal from the position reportingenable/disable switch 427 causes the control unit 431 to either suspendor carry out position reporting from the mobile unit 103 to the centralsite server 107. This feature may be useful, for example, for allowing auser to prevent a remote system from surreptitiously activating theposition reporting mechanism and determining the user's location. Italso allows the user to operate the mobile unit as a standard telephone.

Referring back, now, to FIGS. 3A and 3B, one embodiment for operatingthe system will now be described. In step 301, the mobile unit 103, bydialing a telephone number assigned to the central site server 107,establishes a circuit-switched voice connection with the central siteserver 107 via the cellular telephone network 101 and terrestrialnetwork 105. In response, the central site server 107 uses theestablished connection to transmit a menu of user information-typepossibilities to the mobile unit 103 (step 302). In one aspect of theinvention, the menu may be one that has been previously stored in a massstorage device associated with the central site server 107, and whichrepresents this particular user's preferred selections from a largermenu of selection possibilities.

The menu may be stored in the form of digitized voice signals, which aretransmitted to the mobile unit 103 for playback on the mobile unit'sloudspeaker 415. Upon hearing the menu, the user makes one or moreselections by pressing one or more buttons on the mobile unit's keypad413, thereby causing corresponding dual-tone multifrequency (DTMF)signals to be transmitted back to the central site server 107 via theestablished circuit-switched voice connection. The final such buttonselection transmits a menu tone which signals to the central site server107 that the user has completed the selection process (step 303).Alternatively, the user may simply speak the selection into the mobileunit's microphone if the central site server 107 is equipped with speechrecognition equipment.

In step 304, the central site server 107 receives the selection signalsfrom the mobile unit 103 and converts these into a digital data formatfor internal use by the central site server 107. The converted selectionsignals are then stored in a first data record associated with themobile unit 103. Next, the central site server 107 uses the establishedcircuit-switched voice connection to transmit an end of menu tone to themobile unit 103 which, in conjunction with the menu tone sent by themobile unit 103 (previous step 303), signals to the control unit 431 ofthe mobile unit 103 that both the user and the central site server 107concur that the current menu selection phase has been completed (step305). The control unit 431 instructs the remote DTMF isolation switch433 to send all incoming traffic to the DTMF receiver 435, instructs theloudspeaker/headset isolation circuitry 423 to isolate the loudspeaker415 from locally generated DTMF tones, and instructs the microphoneisolation circuitry 437 to control the microphone switch 439 so as todisconnect the microphone output from the RF modulator 407 (step 306).

In step 307, the control unit of the mobile unit 103 instructs the DTMFgenerator 411 to generate an acknowledge tone to the central site server107. The acknowledge tone acknowledges receipt of the end of menu tone.

The central site server 107 then transmits a request to the mobile unit103 to initiate receipt and processing of position information (step308). This transmission takes place via the established circuit-switchedvoice connection. In another aspect of the invention, the central siteserver 107 also informs the mobile unit 103 of a requested refreshinterval, which specifies how frequently the mobile unit 103 is toreevaluate its position and transmit the reevaluated information to thecentral site server 107.

In response to receipt of the central site server's message, the controlunit 431 of the mobile unit 103 instructs the remote DTMF isolationswitch 433 to direct all future incoming traffic to the loudspeaker 415and enables the GPS receiver 403 to initiate position reporting (step309). The mobile unit 103 receives the signals from the GPS satellites109, and processes these signals in accordance with known techniques todetermine its present location (step 310). The mobile unit 103 alsostores the value of the position refresh interval, if this was alsoreceived from the central site server 107.

After its position has been determined, the mobile unit 103 transmitsthe present location information to the central site server 107 in theform of a sequence of DTMF tones via the established circuit-switchedvoice connection (step 311). A timer is also set so that at the end ofthe position refresh interval, the-process of determining position andtransmitting this information to the central site server 107 will berepeated.

The central site server 107 receives the position information from themobile unit 103 and converts this information into a digital dataformat. The converted position information may then be stored in asecond data record associated with the mobile unit 103. (step 312).Storage of the position information may be useful, for example, if auser is being directed to go from point A to point B; in this case, theposition trend information can be used to correct the user's motion ifthe user is going in the wrong direction. A history of the user'slocation may also be used to prevent information from again being sentto a grid location that the user has been in once before.

After (optionally) storing the position information, the central siteserver 107 uses the converted selection signals from the first datarecord and the position information stored in the second data record toaccess the selection/position table 201 and to retrieve therefrom theselected subset of information 203 (step 313). Of course, theinformation itself need not be stored in the selection/position table201. Those having ordinary skill in the art will recognize that theselection/position table 201 may more conveniently hold only pointers tomass storage locations where the desired data is being retained. In anycase, the retrieved information is then transmitted to the mobile unit103 via the established circuit-switched connection (step 314). As aresult of step 309, the mobile unit 103 will route this information tothe loudspeaker 415 only.

When the mobile unit's timer goes off, the mobile unit 103 againdetermines its position and repeats steps 310 through 314 so long as theuser does not assert a “return to menu” signal (described below) and theestablished circuit-switched connection is not terminated (step 315).Also during this time, the entries in the selection/position table 201may be updated, if the nature of the information stored therein warrantsperiodic updating. In this manner, the mobile unit 103 will continue toreceive the most recent information that corresponds to its presentlocation, even if that location has changed since the last time themobile unit 103 received information.

In accordance with another aspect of the invention, the user may causethe delivery of position-related information to cease by, for example,pressing a button on the mobile unit's keypad which causes the controlunit 431 to instruct the remote DTMF isolation switch 433 to send allincoming traffic to both the loudspeaker and the DTMF receiver 435 (step316) and causes a return to menu tone to be generated by the DTMFgenerator 411 and sent to the central site server 107 (step 317) by theRF modulator/demodulator 407. In response, the central site server 107sends a return to menu phase signal to the mobile unit 103 (step 318)which indicates that the central site server 107 is ready to begin a newmenu selection process. In step 319, the mobile unit 103 confirmsreceipt of the return to menu phase tone from the central site server107 by generating and transmitting an acknowledge signal via theestablished circuit-switched connection. In addition, upon receipt ofthe return to menu phase signal from the central site server 107 and inconjunction with the return to menu signal from the keypad 413, thecontrol unit 431 of the mobile unit 103 instructs theloudspeaker/headset isolation circuit 423 to permit locally generatedDTMF tones to reach the loudspeaker, instructs the microphone isolationcircuit 437 to connect the microphone 409 to the RF modulator 407, andinstructs the GPS receiver 403 to disable position reporting (step 320).

The central site server 107 uses the established connection toretransmit a menu of user information-type possibilities to the mobileunit 103 (step 321). Upon hearing the menu, the user makes one or moreselections by pressing one or more buttons on the mobile unit's keypad413, thereby causing corresponding DTMF signals to be transmitted backto the central site server 107 via the established circuit-switchedvoice connection. The final such button selection transmits a menu tonethat signals to the central site server 107 that the user has completedthe selection process (step 322). Alternatively, the user may simplyspeak the selections into the mobile unit's microphone if the centralsite server 107 is equipped with speech recognition equipment.

In step 323, the central site server 107 receives the selection signalsfrom the mobile unit 103 and converts these into a digital data formatfor internal use by the central site server 107. The converted selectionsignals are then stored in a first data record associated with themobile unit 103. Next, the central site server 107 transmits an end ofreturn to menu tone to the mobile unit 103 which, in conjunction withthe menu tone sent by the mobile unit 103 (previous step 322), signalsto the control unit 431 of the mobile unit 103 that both the user andthe central site server 107 concur that the current menu selection phasehas been completed (step 324). The control unit 431 instructs the remoteDTMF isolation switch 433 to send all incoming traffic to theloudspeaker 415, instructs the loudspeaker/headset isolation circuitry423 to isolate the loudspeaker 415 from locally generated DTMF tones,instructs the microphone isolation circuit 437 to disconnect themicrophone 409 from the RF modulator 407, and instructs the GPS receiver403 to enable position reporting (step 325). The control of the mobileunit 103 then returns to step 310 wherein the mobile unit 103 receivesand processes position information (step 326).

Another way of terminating information delivery is for the user simplyto terminate the telephone call (step 327). In this case, calltermination is detected by the central site server 107, which thenresponds by ceasing information delivery to the particular mobile unit103.

An exemplary embodiment of the central site server 107 for use with theabove-described voice-oriented embodiment will now be described ingreater detail with reference to FIG. 5. The central site server 107 iscoupled to the terrestrial network 105 by means of a digital PBX 501 inaccordance with well-known techniques. This permits the central siteserver 107 to be accessed from any location in which a telephone callcan be initiated.

A second port of the digital PBX 501 is coupled to exchange signals witha voice response unit 503. The voice response unit 503 is a telephonyend point device which accepts mobile unit call set-up requests.

In response to receipt and acceptance of a call set-up request, thevoice response unit 503 sends an audio selection menu to the mobile unit103. The audio selection menu may be stored at the voice response unit503 in the form of digitized voice information. Although the audioselection menu may be standardized for use by all users, in analternative embodiment the menu structure can be set up to recognizerepeat customers and to adjust the options accordingly. This feature mayrequire additional information, such as an inbound phone number or auser's personal identification number (PIN), to be obtained from themobile unit 103. Also, whenever the mobile unit 103 sends DTMF tones tothe central site server 107 (e.g., when the user makes a menu selectionby pressing a button on the keypad 413, or whenever the mobile unit 103sends DTMF-encoded position information to the central site server 107),it is the voice response unit 503 which converts the DTMF tones into theinternally-used digital data format.

The voice response unit 503 further includes digital-to-analog (D/A)circuitry for converting digitally encoded audio data into the audioformat that is used by the mobile unit 103.

Also coupled to the voice response unit 503 is a server 505 whichmaintains the selection/position table 201 for each caller, andretrieves the appropriate digitally-encoded audio narrative from astorage device 507.

Alternative Embodiment Employing Digital Cellular Protocol

In an alternative embodiment, the cellular telephone network 101, aswell as the circuitry within mobile unit 103 which communicates with thecellular telephone network 101, utilize a digital protocol, such as theDigital Advanced Mobile Phone Service (D-AMPS), which is utilized in theUnited States, or the Global System for Mobile Communication (GSM)system which is utilized in Europe. This embodiment uses the digitalfacilities of these new personal communications services (PCS) todeliver information to/from the mobile unit 103 in a digital format overthe public switched telephone network or, in an alternative embodiment,over a public data network such as the Internet. It should be noted thatthe description of the mobile unit herein refers only to selectcomponents of the mobile unit 103. However, it should be noted that themobile unit 103 should also include all of the customary components of astandard digital cellular telephone. A more detailed description of theoperation of this exemplary system will now be described with respect tothe flowchart of FIGS. 6A and 6B, and the block diagram of analternative embodiment of the mobile unit 103 (designated herein as103′), as depicted in FIG. 7.

Turning first to FIG. 7, this discussion will now focus on an exemplaryembodiment of a mobile unit 103′ for use in the digital system describedabove. The mobile unit 103′ includes circuitry for combining digitalcellular telephone components with components necessary for interactingwith the central site server 107′. In connection with the cellulartelephone components, the mobile unit 103′ includes a cellular antenna705, which acts as a wave guide for transmission and receipt of digitalcellular radio frequency (RF) signals. The cellular antenna 705 iscoupled to exchange the digital cellular RF signals with an RFmodulator/demodulator 707. The RF modulator/demodulator 707 receivesoutgoing signals from a communications module 731, and modulates thesesignals onto cellular carrier radio frequencies in accordance with knowntechniques. The communications module 731 adds communication protocolheaders to the outgoing packets (e.g., headers for sending data in atransport control protocol/internet protocol (TCP/IP) network) andremoves the communications-related headers from incoming packets. Thecommunications module 731 supplies incoming packets to, and receivesoutgoing packets from a security element 733. The security element 733may operate in either pass-through mode or in secure mode. When a secureconnection is not requested by the user and is not otherwise required bythe central site server 107′, then the incoming and outgoing digitaltraffic is not modified as it passes through the security element 733.For performing security functions, the security element 733 utilizes anauthentication and key exchange protocol, and includes the followingwell-known elements (not shown): private key; public key cryptoalgorithm; public key certificate; symmetric key crypto algorithm; hashalgorithm; certification authority certificate(s); and random numbergenerator.

The security element 733 receives outgoing packets from a multiplexor729, which in turn receives outgoing packets from one of two sources.One source of those outgoing packets is a microphone 709, which sensesaudio signals in the vicinity of the mobile unit 103′. The microphone709 supplies its signal to an analog to digital converter 735, whoseoutput is supplied to a first data network interface unit 737. The firstdata network interface unit 737 packetizes the digitized voice data, andgenerates addressing for the packets where necessary to identify thesource component and the destination component. Another source ofoutgoing signals is a keypad 713, coupled to a second data networkinterface unit 711. The output of the second data network interface unit711 is supplied to a second input of the multiplexor 729. The keypad 713may be any standard telephone keypad for use in digital mobiletelephones. The illustrated embodiment does not include a separateanalog system for generating DTMF tones. However, in alternateembodiments such circuitry may be advantageous for enabling a user tointerface with devices, such as telephone answering machines, thatexpect to receive DTMF tones.

Another function of the RF modulator/demodulator 707 is to demodulateincoming digital signals from cellular carrier radio frequencies tobaseband frequencies that are used by the mobile unit 103′. Thedemodulated signals are supplied to the communications module 731, whichremoves the communications stack from the incoming packets. Afterpassing through the security element 733, the received packets aresupplied to a packet matching circuit 739 which receives searchparameters from a control unit 741. The search parameters may includebit strings, packet header addresses, and the like. For example, thesearch parameters may designate that the next correct input from thecentral site server 107′ is an “end of return to menu” packet. Thepacket matching circuit 739 compares the received input data stream withthe packet search parameters, and diverts the received packet to aparticular output port whenever a match is detected. A control signalconfirming the match is sent to the control unit 741. If the receiveddata packet does not match the search parameters the received packet isdropped from the traffic stream.

If the received packet is voice data, the packet matching circuit 739passes it to a digital to analog converter 743 whose analog outputsignal is then supplied to a loudspeaker 715. The loudspeaker 715generates audible soundwaves that the user can hear. The mobile unit103′ may also be supplied with a headset 717 which allows the user tolisten to the audio information without disturbing others and withouthaving to hold the mobile unit 103′ up to his ear for prolonged periodsof time.

Turning now to the components that provide the capability of interactingwith the central site server 107′, the mobile unit 103′ further includesa GPS antenna 701 which acts as a wave guide for receipt of wireless GPSposition signals. The GPS antenna 701 is coupled to supply these signalsto a GPS receiver 703. It will be recognized that the GPS signalsemanate from a plurality of GPS satellites 109 in accordance with knowntechniques.

The GPS receiver 703 converts the GPS signals into signals whichrepresent the geographic position of the mobile unit 103′. If enhancedresolution of the mobile unit's position is required, differential GPStechniques may be employed. The output of the GPS receiver 703 issupplied to an input of the second data network interface unit 711,which packetizes the position data, and generates addressing for thepackets where necessary. Under the direction of the control unit 741,the second data network interface unit 711 is also capable of generatingcertain packets, such as an acknowledge signal, as will be described ingreater detail below. As described above, the output packets from thesecond data network interface unit 711 are supplied to a second input ofthe multiplexor 729, so that the position information can betransmitted, through the RF modulator/demodulator 707, digital cellularnetwork 101 and terrestrial network 105 to the central site server 107′.

The GPS receiver 703 is controlled by the control unit 741 and byposition refresh circuitry 719. The control unit 741 determines whetheroperation of the GPS receiver 703 will be enabled or disabled. Theposition refresh circuitry 719 causes the GPS receiver 703 to receiveand process position information at periodic time intervals which may bepredefined, or which may alternatively be dynamically set.

To coordinate the actions of the mobile unit's cellular telephonecomponents with those of the central site server-related components, themobile unit 103′ is further equipped with a position subsystem interface(I/F) module 721. The position subsystem I/F module 721 is coupled toreceive signals from the packet matching circuit 739. These signalsinclude the position request command and position refresh interval valuetransmitted by the central site server 107′ (see description of step 615in FIGS. 6A and 6B).

The position subsystem I/F module 721, then, includes circuitry toenable it, during operation, to receive an initial position requestcommand and a refresh time interval transmitted by the central siteserver 107′, and, in response, to cause the position refresh circuitry719 to initiate a position report. The position subsystem I/F module 721also provides the position refresh circuitry 719 with the value of thereceived position refresh interval, so that the position refreshcircuitry 719 will repeat the position reporting function once everyrequested time interval. The position subsystem I/F module 721 alsosends control signals to the control unit 741 which informs the controlunit 741 of the receipt of a position request command from the centralsite server 107′.

The coupling between the position refresh circuitry 719 and the positionsubsystem I/F module 721 is bidirectional, so that the positionsubsystem I/F module 721 may receive notification of a pending positionrefresh from the position refresh circuitry 719. In another aspect ofthe invention, the mobile unit 103′ is further equipped with amicrophone isolation circuit 745 which controls a switch 747 that isinterposed between the output of the microphone 709 and an input of theloudspeaker 715 and of the analog to digital converter 735. Thisconfiguration allows the control unit 741 to cause the microphoneisolation circuit 745 to prevent the sound signals from the microphone709 from emanating from the loudspeaker 715 (and/or the headset 717) andprevents the sound signals from being conducted to the central siteserver 107′.

In accordance with another aspect of the invention, the control unit 741is also coupled to receive a signal from a position reportingenable/disable switch 727. The signal from the position reportingenable/disable switch 727 causes the control unit 741 to either suspendor carry out position reporting from the mobile unit 103′ to the centralsite server 107′.

Referring back, now, to FIGS. 6A and 6B, one embodiment for operatingthe system will now be described. In step 601, the mobile unit 103′, bydialing a telephone number assigned to the central site server 107′,establishes a circuit-switched data connection with the central siteserver 107′ via a digital PCS, cellular digital packet data (CDPD), orsimilar packetized data network 101 and a terrestrial network 105. Inresponse, the central site server 107′ uses the established connectionto transmit a query asking whether the user wishes to establish a secureconnection (step 602).

At step 603, the user transmits a response by depressing the indicatedbutton on the keypad 713 which generates a signal that is placed into apacket by the second data network interface unit 711. The packet is thentransmitted to the central site server 107′ via the circuit-switcheddata connection. Alternatively, the user may simply provide a voiceresponse which is digitized by the analog to digital converter 735 andpacketized by the first data network interface unit 737, if speechrecognition equipment is available at the central site server 107′.

If the user indicates that a secure connection is not desired and thecentral site server 107′ does not require a secure connection, operationcontinues at step 609 (described below). However, if a secure connectionis desired by the user or required by the central site server 107′, thenthe process continues at step 604, where the central site server 107′uses the established circuit-switched data connection to send its publickey certificate to a security unit contained within the mobile unit103′.

In step 605, the mobile unit 103′ uses the established circuit-switcheddata connection to transmit back to the central site server 107′ amessage that includes a challenge field encrypted using the public keyof the central site server 107‘and the mobile unit’s public keycertificate. Next, at step 606, the central site server 107′ decryptsthe challenge field that was received from the mobile unit 103′ in step605, and sends both the challenge field and a symmetric key back to themobile unit 103′ via the established circuit-switched data connection.This message is transmitted in an encrypted form using a public keyenvelope. Upon receipt of the message, the security element in themobile unit 103′ decrypts the public key envelope and stores thesymmetric key for use in all future transmissions with the central siteserver 107′ for the duration of the call (step 607). That is, allsubsequent transmissions with the mobile unit 103′ will be encryptedusing the symmetric key.

The mobile unit 103′ encrypts the challenge field originally transmittedin step 605 using the symmetric key and sends the encrypted challenge tothe central site server 107′ (step 608).

After receiving the message in step 608, or alternatively afterlearning, in step 603, that the user does not wish to use a secureconnection, the central site server 107′ uses the established connectionto transmit a menu of user information-type possibilities to the mobileunit 103′ (step 609). It will be recognized that this transmission, aswell as all further communications between the mobile unit 103′ and thecentral site server 107′, are encrypted, thereby requiring decryption,if the user elected, in step 603, to use a secure connection.

In one aspect of this invention, the menu may be one that has beenpreviously stored in a mass storage device associated with the centralsite server 107′, and which represents this particular user's preferredselections from a larger menu of selection possibilities.

The menu may be stored in the form of digitized audio signals, which aretransmitted as packets to the mobile unit 103′ for playback on themobile unit's loudspeaker 715 or headset 717. Upon hearing the menu, theuser makes one or more selections by pressing one or more buttons on themobile unit's keypad 713, thereby causing data packets to be sent backto the central site server 107′ via the established circuit-switcheddata connection (step 610). The final such selection indicates that theuser is terminating the selection process. Alternatively, the user maysimply speak the selection into the mobile unit's microphone 709 if thecentral site server 107′ is equipped with speech recognition equipment.The transmission of the user's selections to the central site server107′ is made by way of the digital PCS, CDPD, or similar network 101 andterrestrial network 105.

In step 611, the central site server 107′ stores the selections receivedfrom the mobile unit 103′ in a first data record associated with themobile unit 103′. Next, the central site server 107′ sends a packetconfirming the termination of the menu selection phase (step 612). Instep 613, the control unit 741 instructs the microphone isolationcircuit 745 to isolate the microphone 709 from the analog-to-digitalconverter 735 (and therefore from the multiplexor 729 as well) andinstructs the packet matching circuit 739 to send all incoming packetsto the position subsystem interface module. The mobile unit 103′ sendsan acknowledge packet to the central site server 107′ indicatingreadiness for the next phase of operation (step 614).

Next, the central site server 107′ transmits, via the establishedcircuit-switched data connection, a request to the mobile unit 103′ toinitiate receipt and processing of position information (step 615). Inanother aspect of the invention, the central site server 107′ alsoinforms the mobile unit 103′ of a requested refresh interval, whichspecifies how frequently the mobile unit 103′ is to reevaluate itsposition and transmit the reevaluated information to the central siteserver 107′.

In response to receipt of the central site server's message, the controlunit 741 of the mobile unit 103′ instructs the packet matching circuitryto send all incoming packets to the digital to analog converter 743 forfurther transmission to the loudspeaker 715 and/or headset 717 andenables the GPS receiver 703 to initiate position reporting (step 616).The mobile unit 103′ receives the signals from the GPS satellites 109,and processes these signals in accordance with known techniques todetermine its present location (step 617). The mobile unit 103′ alsostores the value of the refresh interval, if this was also received fromthe central site server 107′.

After its position has been determined, the mobile unit 103′ transmitsthis information to the central site server 107′ via the establishedcircuit-switched data connection (step 618). A timer is also set so thatat the end of the position refresh interval, the process of determiningposition and transmitting this information to the central site server107′ will be repeated.

The central site server 107′ receives the position information from themobile unit 103′ and stores this in a second data record associated withthe mobile unit 103′ (step 619). The central site server 107′ then usesthe selections recorded in the first data record and the positioninformation stored in the second data record to access theselection/position table 201 and to retrieve therefrom the selectedsubset of information 203 (step 620). Those having ordinary skill in theart will recognize that the selection/position table 201 may moreconveniently hold only pointers to mass storage locations where thedesired data is being retained. In any case, the retrieved informationis then transmitted to the mobile unit 103′ via the establishedcircuit-switched data connection (step 621).

When the mobile unit's timer goes off, the mobile unit 103′ againdetermines its position and repeats steps 617 through 621 so long as theuser does not assert a “return to menu” signal (described below) and theestablished circuit-switched connection is not terminated (step 622).Also during this time, the entries in the selection/position table 201may be updated, if the nature of the information stored therein warrantsperiodic updating. In this manner, the mobile unit 103′ will continue toreceive the most recent information that corresponds to its presentlocation, even if the location has changed since the last time itreceived information.

In accordance with another aspect of the invention, the user may press abutton on the mobile unit's keypad 713 (step 650) which causes themobile unit 103′ to send a packet to the central site server 107′indicating the user's desire to halt the receipt of information andreturn to the menu selection phase (step 623). Also, as part of step650, the control unit 741 instructs the packet matching circuitry 739 tosend data packets to the loudspeaker 715 or the control unit 741 andinstructs the microphone isolation circuit 745 to connect the microphone709 to the analog to digital converter 735 (and therefore to themultiplexor 729 as well). In step 624, the central site server 107′ceases the delivery of information content and responds with aconfirmation packet. The mobile unit 103′ generates and transmits anacknowledge signal in order to acknowledge receipt of the confirmationpacket (step 625). The control unit 741, having received the user'sinput of step 623 and the central site server's confirmation packet ofstep 624, responds by instructing the GPS receiver 703 to halt thedelivery of position refresh to the data network interface (step 626).

In step 627, the central site server 107′ uses the establishedconnection to transmit a menu of user information-type options to themobile unit 103′ (step 627). Upon hearing the menu, the user makes oneor more selections by pressing one or more buttons on the mobile unit'skeypad 713, thereby causing data packets to be sent back to the centralsite server 107′ via the established circuit-switched data connection(step 628). The final such selection indicates that the user isterminating the selection process. Alternatively, the user may simplyspeak the selection into the mobile unit's microphone if the centralsite server 107′ is equipped with speech recognition equipment. Thetransmission of the user's selections to the central site server 107′ ismade by way of the digital PCS, CDPD, or similar network 101 andterrestrial network 105.

In step 629, the central site server 107′ stores the new selectionsreceived from the mobile unit 103′ in the first data record associatedwith the mobile unit 103′. Next, the central site server 107′ sends apacket confirming the termination of the menu selection phase (step630). In step 631, the control unit 741 instructs the GPS receiver 703to resume the delivery of position refreshes, directs thatpackets/content go to the loudspeaker 715 only, and directs themicrophone isolation circuitry 745 to disconnect the microphone 709 fromthe loudspeaker 715 and the analog to digital converter 735 (andtherefore from the multiplexor 729 as well). The mobile unit 103′ sendsan acknowledge packet to the central site server 107′ indicatingreadiness for the next phase of operation (step 632). The mobile unit103′ returns to the state set forth in step 617 (step 633).

Another way of terminating information delivery is for the user simplyto terminate the telephone call (step 634). In this case, calltermination is detected by the central site server 107′, which thenresponds by ceasing information delivery to the particular mobile unit103′.

An exemplary embodiment of a central site server 107′ for use with theabove-described digital embodiment will now be described in greaterdetail with reference to FIG. 8. The central site server 107′ is coupledto the terrestrial network 105 by means of a remote dial-up accessserver 801 in accordance with well-known techniques. This permits thecentral site server 107′ to be accessed from any location in which adigital PCS, CDPD or other circuit-switched packet data call can beinitiated.

A second interface of the remote access server 801 is coupled to asecurity element 802. The remote access server 801 supplies incomingdata packets to a security element 802 and receives outgoing datapackets from the security element 802. The security element 802 mayoperate in either pass-through mode or in secure mode. When a secureconnection is not requested by the user, then the incoming and outgoingdigital traffic is not modified as it passes through the securityelement 802. For performing security functions, the security element 802utilizes an authentication and key exchange protocol, and includes thefollowing well-known elements (not shown): private key; public keycrypto algorithm; public key certificate; symmetric key cryptoalgorithm; hash algorithm; certification authority certificate(s); andrandom number generator.

A second interface of the security element 802 is coupled to a server805. The security element 802 supplies incoming data packets to theserver 805 and receives outgoing data packets from the server 805. Theserver 805 maintains the selection/position table 201 for each caller,and retrieves the appropriate digitally-encoded audio narrative ordata/multimedia presentation from a storage device 807.

In accordance with another aspect of the invention, the system fordelivering position-related information to a mobile user may furtherinclude a universal emergency response capability. In response toreceipt of an emergency response request from the mobile unit 103, thecentral site server 107 contacts an emergency operations center andtransmits the location of the mobile unit 103 to an emergency center.The central site server 107 also forwards the connection with the mobileunit 103 to the emergency operations center in order to permit two-wayreal-time communication between the customer (mobile user) and theemergency operations center. During this communication, the central siteserver 107 may further provide the emergency operations center withcontinuous updates of the customer's position. This system is applicableto pedestrians as well as to customers riding in vehicles.

From the descriptions above, a number of advantages of the inventivemobile unit information system become evident. First, the informationavailable to the user is not dependent on the loading of a storagedevice on the mobile platform or individual. Wherever the mobile unit istaken, information is available on short notice and effortlessly linkedto the mobile unit's location. No agency or establishment has topre-position a device, sign, literature or sensor in advance of themobile unit's arrival. Perishable information is updated as eventsoccur, thereby avoiding becoming quickly outdated, in contrast toinformation that is pre-positioned within the mobile unit.

Another advantage is the fact that the information requested isavailable year round and at all hours of the day.

Still another benefit of the invention is the fact that the range ofinformation available is broad and can be tailored to the desires andneeds of the mobile unit operator. Last minute decisions aboutitineraries and routes are easily accommodated because information isprovided in correspondence with the user's actual position, as opposedto basing it on an expected position that may or may not be accurate.

Also, the light weight, easily hand carried mobile unit 103 permitsoperation where vehicles could not pass or are not permitted. Likewise,emergencies which occur away from a base station or vehicle can bereacted to with vast amounts of pertinent site specific information maderapidly available to responding units or agencies.

The invention has been described with reference to a particularembodiment. However, it will be readily apparent to those skilled in theart that it is possible to embody the invention in specific forms otherthan those of the preferred embodiment described above. This may be donewithout departing from the spirit of the invention. For example, thesystem is not limited to use of the GPS, but may alternatively employother universal positioning information sources. In one alternativeembodiment, the universal positioning information source may be apositioning system that responds to a first signal transmitted by themobile unit 103 by generating raw position signals and transmittingthese back to the mobile unit 103. The mobile unit 103 may generate thepresent position information from the received position signals, andtransmit the present position information to the central site server 107as described above. Alternatively, the mobile unit 103 may forward theposition signals to the central site server, and the central site servermay include means for generating the present position information fromthe position signals.

In another alternative, the positioning system may respond to receipt ofthe first signal from the mobile unit 103 by sending informationdirectly to the central site server 107 instead of to the mobile unit103. The information may be the raw position signals, in which case thecentral site server 107 includes means for generating the presentposition information from the received position signals. Alternatively,the positioning system may generate usable present position informationitself, and transmit this directly to the central site server 107. Thepositioning system in this case also transmits a signal identifying thisparticular mobile unit 103, so that the central site server 107 canassociate the received present position information with this mobileunit's connection.

In another variation, the positioning system, in response to receipt ofthe first signal from the mobile unit 103, generates the usable presentposition information and transmits this back to the mobile unit 103,which then forwards the present information to the central site server107.

Furthermore, the system can accommodate output devices which are digitalor analog, including laptop PCs, hand-held video receivers, 3-Dmultimedia audio/visual headsets, and the like. Thus, the user need notbe restricted to reception of only voice or text information, but mayuse any of a variety of well-known means for supplying responseinformation.

The preferred embodiment is merely illustrative and should not beconsidered restrictive in any way. The scope of the invention is givenby the appended claims, rather than the preceding description, and allvariations and equivalents which fall within the range of the claims areintended to be embraced therein.

1. A mobile communication device for use by a mobile user, comprising:an input device configured to receive from an operator a selectionsignal indicative of a topic of interest; a receiver configured toreceive position signals from a satellite positioning system; means forsending present position information of the mobile communication deviceand the selection signal over a bi-directional wireless link; and meansfor receiving position-related information that is a function of thepresent position information and the selection signal.
 2. The mobilecommunication device of claim 1, wherein the topic of interest isselected from a plurality of topics of interest.
 3. The mobilecommunication device of claim 1, wherein said input device comprises akeypad and the selection signal corresponds to an alphanumeric entry onsaid keypad.
 4. The mobile communication device of claim 3, furthercomprising a dual tone multi-frequency (DTMF) generator responsive tothe alphanumeric entry to supply a DTMF selection signal to the meansfor sending.
 5. The mobile communication device of claim 1, furthercomprising a microphone having an output coupled to the means forsending, for transmitting audio signals over the bi-directional wirelesslink.
 6. The mobile communication device of claim 5, wherein said inputdevice comprises said microphone and the selection signal comprises avoice signal received by said microphone.
 7. The mobile communicationdevice of claim 5, further comprising a microphone isolation circuitconfigured to disconnect an output of said microphone from the means forsending during reception of the position-related information.
 8. Themobile communication device of claim 1, further comprising a speakerconfigured to emanate audible signals comprising a menu of selectabletopics of interest.
 9. The mobile communication device of claim 8,further comprising a speaker isolation circuit configured to preventaudio signals corresponding to the position information from emanatingfrom said speaker.
 10. The mobile communication device of claim 1,wherein said mobile communication device comprises an analog wirelesstelephone.
 11. The mobile communication device of claim 1, wherein saidmobile communication device comprises a digital wireless telephone. 12.The mobile communication device of claim 1, wherein said mobilecommunication device comprises a laptop computer.
 13. The mobilecommunication device of claim 1, wherein said mobile communicationdevice receives position-related information which includes audiosignals.
 14. The mobile communication device of claim 1, wherein saidmobile communication device receives position-related information whichincludes text signals.
 15. The mobile communication device of claim 1,wherein said mobile communication device receives position-relatedinformation which includes image signals.
 16. The mobile communicationdevice of claim 1, wherein said mobile communication device receivesposition-related information which includes video signals.
 17. Themobile communication device of claim 1, wherein said mobilecommunication device is configured to send over the bi-directionalwireless link an emergency response request destined for an emergencyresponse system.
 18. The mobile communication device of claim 1, furthercomprising: a processor coupled to the receiver and responsive to theposition signals to determine the present position informationindicative of a present position of the mobile communication device. 19.The mobile communication device of claim 18, wherein the receivercomprises a global positioning system (GPS) receiver.
 20. The mobilecommunication device of claim 1, wherein the present positioninformation comprises position coordinates.
 21. The mobile communicationdevice of claim 18, wherein the processor periodically determines theposition information from position signals received by the receiver, andthe means for sending periodically transmits the position informationover the bidirectional wireless link.
 22. The mobile communicationdevice of claim 21, wherein the processor periodically updates theposition information in accordance with a refresh interval.
 23. Themobile communication device of claim 1, wherein the present positioninformation comprises the position signals.
 24. The mobile communicationdevice of claim 1, further comprising: output means for providing theposition-related information to the mobile user.
 25. The mobilecommunication device of claim 1, further comprising: a positionreporting enabling unit configured to selectively enable and disabletransmission of the position information while said mobile communicationdevice is operational.
 26. The mobile communication device of claim 1,wherein the input device receives a plurality of selection signals, andthe means for sending sends the plurality of selection signals over thebi-directional wireless link.
 27. The mobile communication device ofclaim 1, wherein the mobile communication device comprises a portablecomputing device.
 28. A method of receiving position-related informationvia a mobile communication device, the method comprising: supplying aselection signal indicative of a topic of interest to the mobilecommunication device; receiving position signals from a satellitepositioning system; sending present position information of the mobilecommunication device and the selection signal over a bi-directionalwireless link from the mobile communication device; and receiving overthe bidirectional wireless link position-related information that is afunction of the present position information and the selection signal.29. The method of claim 28, further comprising: processing the positionsignals to determine the present position information indicative of apresent position of the mobile communication device.
 30. The method ofclaim 29, wherein processing comprises periodically processing todetermine position information from position signals from said receivingposition signals; and sending comprises periodically sending positioninformation over the bidirectional wireless link.
 31. The method ofclaim 30, wherein periodically processing comprises periodicallyupdating the position information in accordance with a refresh interval.32. The method of claim 28, wherein the present position informationcomprises the position signals.
 33. The method of claim 28, furthercomprising: selecting the topic of interest from a plurality of topicsof interest.
 34. The method of claim 28, wherein supplying comprisessupplying with an input device including a keypad, and wherein theselection signal corresponds to an alphanumeric entry on said keypad.35. The method of claim 34, further comprising: generating a dual tonemulti-frequency (DTMF) in response to the alphanumeric entry; whereinsupplying comprises supplying a DTMF selection signal; and whereinsending comprises sending the DTMF selection signal.
 36. The method ofclaim 28, wherein the mobile communication device includes an inputdevice configured and arranged to input audio signals and having anoutput, and further comprising: transmitting audio signals over thebi-directional wireless link.
 37. The method of claim 36, wherein saidinput device comprises a microphone, and supplying comprises supplying aselection signal including a voice signal received by said microphone.38. The method of claim 36, wherein the input device includes amicrophone having an output and a microphone isolation circuitconfigured to disconnect the microphone output, and comprising:disconnecting the microphone with the microphone isolation circuitduring receiving position-related information.
 39. The method of claim28, further comprising: generating audible signals including a menu ofselectable topics of interest.
 40. The method of claim 39, furthercomprising: preventing audio signals corresponding to the positioninformation from being generated.
 41. The method of claim 28, whereinsaid mobile communication device comprises an analog wireless telephone.42. The method of claim 28, wherein said mobile communication devicecomprises a digital wireless telephone.
 43. The method of claim 28,wherein said mobile communication device comprises a laptop computer.44. The method of claim 28, wherein receiving position-relatedinformation comprises receiving audio signals.
 45. The method of claim28, wherein receiving position-related information comprises receivingtext signals.
 46. The method of claim 28, wherein receivingposition-related information comprises receiving image signals.
 47. Themethod of claim 28, wherein receiving position-related informationcomprises receiving video signals.
 48. The method of claim 28, furthercomprising: sending over the bi-directional wireless link an emergencyresponse request destined for an emergency response system.
 49. Themethod of claim 28, wherein receiving position signals comprisesreceiving global positioning system (GPS) signals.
 50. The method ofclaim 28, wherein receiving position signals comprises receivingposition coordinates.
 51. The method of claim 28, further comprising:providing position-related information to the mobile user.
 52. Themethod of claim 28, further comprising: selectively enabling anddisabling said sending of the position information, said selectivelyenabling and disabling performed while said mobile communication deviceis operational.
 53. The method of claim 28, comprising: receiving aplurality of selection signals; and wherein sending comprises sendingthe plurality of selection signals over the bidirectional wireless link.54. The method of claim 28, wherein the mobile communication devicecomprises a portable computing device.
 55. The method of claim 28,wherein sending present position information comprises sending positioncoordinates.